The present invention relates to a system for handling coiled electrical conductors for providing connection to movable elements and has been developed in the connection with overcoming problems that arise where a power connection must be provided to a movable motor. Such an application is employed in long retracting sootblowers wherein the motor and the supporting carriage travel with a long lance tube. Sootblowers are used to project a stream of blowing media such as water or steam against internal surfaces of large scale boilers for removing slag and ash encrustations. Due to the high temperature within the boiler, retracting sootblowers are often used in which a lance tube is periodically advanced into and withdrawn from the boiler during the cleaning cycle.
The sootblower carriage motor and lance tube are typically supported on tracks carried by a substantially horizontal beam structure. The carriage is arranged to travel along the beam for distances which may be as great as 50 or more feet. The motor may be either electric or air powered. Various power feeding means of an extendable and retractable character have been employed. In boiler environments where sootblowers are utilized, several factors tend to shorten equipment life. Such factors include heat, vibration and the presence of abrasive fly ash in the atmosphere. Sliding electrical contacts are inefficient and undesirable in such environments, so that some form of continuous cable is desirable to supply electric power. The life of electric cables employed in this service has been less than satisfactory, however, due to the repeated flexing of the cable as well as the factors above mentioned.
U.S. Pat. No. 3,819,880 issued Jun. 25, 1974, commonly assigned and incorporated herein by reference, discloses one solution to this problem which has been found commercially practical and which has been successfully employed. In this apparatus, a helically coiled flexible electric cord is supported upon a rod extending in the direction of travel of the sootblower motor and carriage. The system provides a controlled extension and retraction of the coiled conductor for reducing stress on the conductor thereby increasing operating life.
As described in the above mentioned patent, a cable guiding sleeve is slidably carried along the rod and is of sufficient length to store the helical coils when the sootblower is in a retracted position. The sleeve is coupled to the sootblower carriage and motor so as to move along the rod as the sootblower is extended into and retracted from the boiler. However, because the sootblower motor and carriage are carried upon a beam structure separate from the rod supporting the sleeve, the desired alignment of the sleeve and rod is not always achieved. The result is increased wear along the inner surface of the sleeve as the sleeve travels along the rod. In an effort to provide proper alignment it is typically necessary to bend the tow brackets used to couple the sleeve with the sootblower carriage. However, due to variations in the alignment of the rod and the support beam along their lengths, it is difficult to maintain proper alignment between the rod and carriage over the long lengths of travel required.
Accordingly, it is an object of the present invention to improve the alignment of a sootblower conductor coil sleeve with the supporting rod to reduce wear of the sleeve.
It is a feature of the present invention to decouple the sleeve from the sootblower motor and carriage so that the only forces applied to the sleeve are axial forces necessary to move the sleeve along the rod, leaving the sleeve free to move vertically and angularly to align itself with the rod.
It is a further feature of the present invention that the sleeve is free to rotate about the rod. As the sleeve is moved along the rod and coils of the coiled conductor are payed out over a knob at the end of the sleeve, the coil sliding over the knob causes slight rotation of the sleeve with the result that wear along the inside of the sleeve is evenly distributed about the sleeve's inner circumference.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.